code: def _calc_datagrad_on_defense(defense, data):
      data = data.detach().clone().requires_grad_()
      loss = defense(data).sum()
      loss.backward()
      return data.grad.detach().clone()
  
file_path: advertorch/tests/test_bpda.py
imports: import itertools
  import pytest
  import torch
  import torch.nn
  from advertorch.bpda import BPDAWrapper
  from advertorch.utils import torch_allclose
  from advertorch.test_utils import withgrad_defenses
  from advertorch.test_utils import nograd_defenses
  from advertorch.test_utils import defense_kwargs
  from advertorch.test_utils import defense_data
  from advertorch.test_utils import vecdata
label_desc: Use image node_id 3 for calling a global function with example usage: _calc_datagrad_on_defense(defense, data) and returns: data